One of the components of the mass spectrometry workgroup mission is to provide other groups within NIEHS access to mass spectrometric analyses on a service basis. The workgroup provides the following services on an ongoing basis: 1) low and high resolution electron impact (EI) mass spectra; 2) low and high resolution chemical ionization (CI) mass spectra; 3) negative ion chemical ionization (NICI) mass spectra; 4) gas chromatography/mass spectrometry (GC/MS) in conjunction with EI, CI and NICI mass spectra; 4) gas chromatography/mass spectrometry (GC/MS) in conjunction with EI, CI and NICI MS; 5) thermospray (TSP) liquid-chromatography/mass spectrometry (LC/MS) in conjunction with CI and NICI MS; 6) electro-spray ionization; 7) electro-spray ionization; 8) fast atom bombardment (FAB) under both positive and negative ion conditions; 8) continuous flow FAB/MS and FAB/MS/MS under both positive and negative ion conditions; and 10) tandem MS in combination with positive and negative ion FAB, EI and CI MS. During the past year approximately 630 MS analyses have been performed on a service basis (not including collaborative work). In addition to mass spectrometric services provided to other NIEHS scientists, we have been called upon to provide high performance liquid chromatographic (HPLC) support. With the addition of capillary zone electrophoresis (CZE) capabilities in this lab, these service aspects are expected to increase in importance.